Assessing the efficacy of iso-mukaadial acetate and betulinic acid against selected Plasmodium falciparum glycolytic pathway proteins: in silico and in vitro studies

Malaria is the extensive health concern in sub-Saharan Africa, with Plasmodium falciparum being the most lethal strain. The continued emergence of drug-resistant P. falciparum advocates for the development of new antimalarials. Our current study aimed to effectively explore the interaction capabilities of iso-mukaadial acetate (IMA) and betulinic acid (BA) against two essential P. falciparum glycolytic pathway proteins, PfLDH and PfHk. Recombinant PfLDH and PfHk were independently expressed in E. coli BL21 (DE3) cells and subsequently purified using affinity chromatography. Protein–ligand interaction studies probed in silico and in vitro approaches. Parasite inhibition studies confirmed potent antimalarial activity against the P. falciparum NF54 strains, with BA and IMA showing IC₅₀ values of 1.27 µg/ml and 1.03 µg/ml against the asexual stage of P. falciparum, respectively. FTIR experiments confirmed interactions between the compounds and the secondary structure of the proteins. Direct protein–ligand interaction studies analysis using microscale thermophoresis (MST) showed a K_D value of 0.1036 ± 0.6001 µM for the PfLDH-BA complex and 0.7473 ± 0.3554 µM K_D value for PfLDH-IMA. Meanwhile, PfHk-IMA had 0.39701 ± 0.16298 µM K_D value, while the PfHk-BA complex had no interaction detected. Molecular docking and molecular dynamics simulation studies were used to measure and confirm the interactive strength of complexes. Molecular docking reported a binding score of − 1.155 kcal/mol for the PfLDH-BA complex and a binding score of − 3.200 kcal/mol for PfLDH-IMA. The PfHk-BA complex had − 2.871 kcal/mol and PfHk-IMA complex had − 4.225 kcal/mol binding score. In conclusion, BA and IMA compounds had better interactions and remained bound within the binding sites of the glycolytic pathway proteins (PfLDH and PfHk).